Discordance at human leukocyte antigen-DRB3 and protection from human immunodeficiency virus type 1 transmission.

Host human leukocyte antigens (HLAs) integrated into the human immunodeficiency virus (HIV) type 1 envelope could theoretically determine, as in tissue transplants, whether HIV-1 is "rejected" by exposed susceptible persons, preventing transmission. HLA discordance (mismatch) was examined among 45 heterosexual partner pairs in which at least 1 partner was HIV-1 infected and exposure or transmission between partners had occurred. Immunologic discordance at class II HLA-DRB3 (present in the HIV donor partner but absent in the recipient partner) was associated with lack of transmission of HIV-1.